In connection with the care and treatment of wounds, the term "wound" is meant to include burns, pressure sores, punctures, ulcers and the like. For a long time, one critical aspect of wound care has been the consideration of the requirements of the epithelium, i. e., that area of new cell growth directly peripheral to the wound which is formed during the healing process, so that healing is facilitated.
Since it has been recognized that healing of the wound occurs in one sense as the epithelium migrates by growth from the periphery inward, care has been taken not to damage unnecessarily or to irritate this new area of growth or existing, compromised periwound tissue. With many dressings, problems can occur during dressing changes. This is particularly true where the dressing adheres to the epithelium or where granulation tissue and new cell growth become intertwined within the matrix of a dressing. In these instances, there is a risk that removal of the dressing will damage the sensitive tissue and new growth on the periphery of the wound thereby causing a regression in the progress of wound healing.
Another consideration in wound care is the frequency of dressing changes. The time frame for the changing of dressings depends on many concerns and therefore opinions as to how often dressings should be changed vary drastically.
Still, another important consideration in wound care is the needs of the surrounding unwounded skin. The unwounded skin beyond the epithelium is usually in contact with some portion of the wound dressing system which maintains the dressing positioned on the wound. For example, the surrounding skin may be covered for extended periods with a wrap and/or adhesive to hold the dressing in place. Many such dressings can irritate this surrounding skin and compound problems to the patient. This is especially true in the area of leg ulcers wherein the surrounding skin can easily become sensitized by strong medicaments and is often plagued with flaking, scaling and eczema.
One type of treatment presently used, in particular for leg ulcers, comprises the application of gauze to the ulcer and the utilization of a compression wrap to secure the gauze to the ulcer. Since the gauze quickly becomes saturated, frequent changes are necessary and damage to the epithelium and surrounding skin may occur. Moreover, if the gauze is left on for too long a period, the exudate can begin to overly hydrate and macerate the patient's surrounding skin.
A second type of treatment, also used in particular for leg ulcers, is the Unna's Boot (commercially available from Biersdorf, Inc.) which comprises a zinc paste-containing bandage wrapped around a patient's leg from above the toes to below the knee. Other Unna's Boot/zinc impregnated treatments are available from Miles and Graham Field. These dressings are typically left in place for a week at a time and absorbent pads must be applied to the outside of the dressings in the area of the ulcer to absorb excess exudate. Seepage of exudate throughout the wrap is common, and damage to the skin and epithelium is inevitable.
Another type of wound dressing is disclosed in U.S. Pat. No. 5,106,362 to Gilman. This dressing is provided with a base sheet for contacting the skin of a patient. The base sheet has an opening for placement over the wound. The dressing has a vent for providing controlled leakage of fluid along a path from the wound through the opening of the base sheet. The vent is designed to provide control over wound leakage along a "tortuous path" from the wound through the opening of the base sheet.
A modification of the dressing of U.S. Pat. No. 5,106,362 is disclosed in U.S. Pat. No. 5,056,510, also to Gilman. The '510 patent discloses a vented dressing where the fabric reservoir for wound exudate is contained within a chamber. The walls of the chamber are intended to provide a barrier to bacterial and other contaminants. The walls of the chamber are also intended to be air permeable so as to permit egress of air from the voids of the fabric reservoir. These Gilman dressings do not especially address the problems of the epithelium and the surrounding skin.
U.S. Pat. No. 4,909,243 to Frank et al., which is owned by the assignee of the present invention, discloses a two piece wound dressing comprising a baseplate having an adhesive surface for contacting surrounding skin. The baseplate has an aperture extending completely through the baseplate and around the wound over which a wound pad of a desired wound dressing material can be placed. The purpose of the aperture is to permit visualization of the wound.
U.S. Pat. No. 4,485,809 to Dellas relates to a film window dressing. There is a central region or window defined by perforation lines which is applied to a patient. The perimeter or window frame which is used to permit easier handling is then removed.
It is apparent that, considering the various types of wounds, the numerous dressings that are available, and the various stages of healing, there is still a tremendous need for a dressing that functions better than the current dressings, especially with respect to preventing damage to surrounding skin, tissue and new cell growth. In particular, a wound dressing system which protects the epithelium and surrounding non-wounded skin, which wicks away moisture from the wound area, and which does not purposely adhere to the wound or the surrounding area would be a useful addition to the wound care art. A dressing for patients with fragile skin surrounding a wound would be especially beneficial.